Thank you for all the responses, especially for what ended up being the "dissenting" opinions in favor of the Sigma.

I was looking for thoughts on how the focal lengths compare, or if they're even comparable at all. It seems the two are very (?) different beasts. If anyone else has input it would be appreciated.

As to being a "gear hound," I didn't realize having 1 camera (a low-end model, at that) and all of 3 lenses besides those in question would qualify me as a "gear hound." In fact, I imagine that puts me in the distinct minority compared to most members of these forums.